LONDON (Reuters) - Britain's new plastic five-pound notes, bearing the portrait of wartime Prime Minister Winston Churchill, have fallen foul of thousands of people who object to the use of animal fats in their manufacture.

An online petition against the notes, started by campaigner Doug Maw, was signed by more than 13,000 supporters in less than 24 hours.

"This is unacceptable to millions of vegans and vegetarians in the UK," Maw wrote in the online petition.

"We demand that you cease to use animal products in the production of currency that we have to use," the petition continued, adding that some religious groups may also object.

The Bank of England confirmed that tallow, which contains animal fats, is used in the production of the new currency, and said the substance was also commonly used in candles and soap.

"We can confirm that the polymer pellet from which the base substrate is made contains a trace of a substance known as tallow," a Bank spokeswoman said.

The new, light-blue five pound notes are worth just over $6 and were introduced in September. They are smaller and stronger, with more security features than their predecessors, with the aim of making them harder to counterfeit.

A plastic 10-pound note featuring the author of "Pride and Prejudice", Jane Austen, is due to appear next year.

(Reporting by Adela Suliman; editing by Stephen Addison and David Milliken)